Hello Takashi, I'm sorry as this is getting bit confusing for me. Playing the PCM data I would want to pass the starting physical address of this location to the DMA start address. Now can I access "dma_addr" directly for this purpose? Do I still have to allocate DMA memory or will just passing of this dma_addr as source address suffice? I am new to ALSA framework and it's getting a bit confusing to me. Regards; Aadish On Thu, Jun 24, 2010 at 1:14 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: > At Thu, 24 Jun 2010 12:52:47 +0530, > Adish Kuvelker wrote: >> >> Hello, >> >> If I use "SNDRV_DMA_TYPE_CONTINUOUS" as a parameter to pre-allocate >> function to get contiguous locations of memory and use the function >> snd_dma_continuous_data() would that be correct setting for my case? > > I guess no. As mentioned, it's no DMA memory, i.e. simple pages > allocated via __get_free_pages() and co. > >> Where are the parameters of dma_addr and dma_area written to the >> runtime structure? > > These are available only for pages properly allocated for DMA. > > > Takashi > >> >> Regards; >> Aadish >> >> On Thu, Jun 24, 2010 at 12:45 PM, Takashi Iwai <tiwai@xxxxxxx> wrote: >> > At Thu, 24 Jun 2010 12:38:35 +0530, >> > Adish Kuvelker wrote: >> >> >> >> Hello Takashi, >> >> >> >> I am developing a DMA Controller driver to service the PCM out data to >> >> the Audio controller on the arm-based ATLASIII procesor. In case you >> >> need any more information on the architecture I can pass. >> >> >> >> Since the DMA isn't on PCI bus I am pre-allocation continuous memero >> >> using the "snd_pcm_lib_preallocate_pages_for_all" passing >> >> SNDDRV_DMA_TYPE_DEV and "snd_dma_continuous_data" as appropriate >> >> parameters. >> > >> > snd_dma_continuous_data() is only for SNDRV_DMA_TYPE_CONTINUOUS. >> > In this case, the pages aren't for DMA. >> > >> > For SNDRV_DMA_TYPE_DEV, simply pass the device pointer you use. >> > >> > >> > Takashi >> > >> > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel